1894.1 



AN ATTEMPT TO ACCOUNT FOE MOTH-aREASE, WITH NOTES ON 

 ITS CURE BY ETHER. 



BY H. GUAED KNAGGS, M.D., F.L.S. 



Moth-grease, I take it, is a fuel food stored up chiefly by larvae as 

 a provision against starvation on the one hand, and as a protection 

 against the effects of cold and wet on the other, and no doubt also as 

 a reserve of energy to be used up in the violent exertion of flight, &c., 

 and those species which lay- in the biggest stock of it give most trouble 

 to collectors. Of these, first come the internal feeders which inhabit 

 wood, bark, stems, roots, fruits, seed-heads, also those which eat fungi 

 or make galleries in dried fruits, fabrics, furs, nests of Ryvienoptera, 

 refuse, &c. ; the majority of all these pass the winter in the larval 

 state : next come those which feed underground on roots, or which 

 pass a large portion of their time below ground, or conceal themselves 

 under sods, stones, and similar situations ; these, too, generally hiber- 

 nate as larvae. All the preceding live more or less in the dark, secluded 

 from the air, and restricted in their movements. Web-makers, the 

 imagines of which also have a tendency to grease, come under the 

 category, but to a less extent : then other larvae, generally hibernators, 

 produce Somhyces, most of which family are deficient in suctional 

 power, and the males of which are most vigorous on the wing ; these 

 would fare ill had they not, as caterpillars, stocked themselves with 

 an ample supply of fuel food. Another set of larvae which do not 

 hibernate have to make preparation for the time when they will have 

 to appear in the imago state in the colder months of the year ; these 

 generally accumulate considerable quantities of fatty matter ; the 

 autumn batch, in the winged state, procuring additional stores of 

 nutriment more particularly from the blossoms of the ivy to enable 

 them to tide over the winter mouths, and resume their orgies at the 

 sallows that bloom in the spring. 



Males are more affected with grease than females, which may be 

 accounted for by the male larva stocking intuitively a considerable 

 supply of reserved energy in readiness for its arduous exertions in 

 the winged state, while the female beiug of a more sedate turn is 

 content with a moderate amount. Then, again, bred specimens go 

 greasy far more frequently than those which have been taken on the 

 wing. It has also been suggested to me by a correspondent that 

 insects which have paired rarely grease, and those which have paired 

 a second time never. Now, as no one, except for breeding require- 



